The present invention relates to flow meters in general, and in particular to flow meters employing a paddle perpendicular to the direction of measured flow.
Devices that sense the flow of water in an essentially binary manner, i.e. determining whether flow is or is not present, are used in many systems which handle water, for example, boilers, shower pumps, and water tanks. In many instances, equipment may be damaged if it continues to operate when water is not flowing. A water pump, for example, may overheat if no water is flowing. A class of devices which may be referred to as paddle flow sensors provide a simple reliable mechanism for detecting water flow. Such a device has a pivot arm, on one end of which is a paddle and on the other end of which is a magnet. The paddle extends into a pipe so that water flowing in the pipe presses against the paddle, causing the magnet opposite the paddle to move and to thereby activate a reed switch. For example, U.S. Pat. No. 5,183,983 teaches a vane assembly that is pivotally mounted to a pin and has a portion which extends downwardly into a flow pipe. The portion of a vane assembly opposite the portion that extends into the flow pipe has a magnet that moves in response to water pressure against the downwardly extending portion. Motion of the magnet causes a reed switch to change state from open to closed, or from closed to open, depending upon the adjustable position of the reed switch.
Although such flow indicating switches are widely used, there is a need for greater simplicity in their assembly and construction and adaptability to function with various magnetic field sensors, which could provide more than binary flow information.
The flow sensor of the present invention is constructed largely of plastic, especially those components that come into contact with water. Typically all materials which come into contact with water will meet the various regulatory requirements for materials coming into contact with potable water. The flow sensor is constructed of relatively few parts that are assembled with a minimum of fasteners. The flow sensor has a paddle assembly that has a paddle at one end and an activation magnet at the other end. The paddle assembly is pivotally mounted to a housing by opposed pivot posts that extend from the paddle assembly between the paddle and the magnet. The housing has two resilient pivot post clips integrally formed with the housing. The paddle assembly is assembled to the housing by sliding the opposed pivot posts along grooves in the pivot post clips until the posts are received in mounting holes, whereupon the pivot post clips resiliently spring inwardly to capture the pivot posts and thus the paddle assembly. The housing is attached by a compression nut to a pipe fitting on a pipe through which water flow is to be monitored. A shroud surrounds the housing and positions a biasing magnet which repels the magnet on the paddle assembly, holding the paddle assembly in the non-activated position when water is not pressing on the paddle. The shroud slides over the housing and provides a transverse passageway that is aligned with a passageway in the housing. An activation sensor within a sleeve is positioned within the transverse passageway of the housing and passes through the transverse passageway of the shroud pinning the two subassemblies together. The sleeve is held in one of two positions on the shroud by an e-clip. The e-clip, by fixing the sleeve to the shroud, also pins the shroud to the housing. The sensor within the sleeve may be a reed switch, and is positioned by the sleeve and the e-clip so that motion of the activation magnet mounted on the paddle assembly causes the reed switch to change state, from closed to open or from open to closed.
It is a feature of the present invention to provide a flow sensor with simplified construction.
It is a further feature of the present invention to provide a flow sensor that is resistant to wet and dusty environments.
It is another feature of the present invention to provide a flow sensor that can be adjusted in the field.
It is a yet further feature of the present invention to provide a flow sensor that can be assembled with a minimum of fasteners.